Blasting plug



Jul 2, 1946. B. L. LUBELSKY ET AL 2,403,335

BLASTING PLUG Filed Jan. 50, 1941 5 Sheets-Sheet l llllll J WMJMM Mam MB. L. LUBELSKY ET AL BLASTING PLUG Filed Jan. 50, 1941 5Sheets-Sheet 2July 2, 1946.

y 1946- B. LUBELSKY ET AL 2,403,386

BLASTING PLUG Filed Jan. 50, 1941 3 Sheets-Sheet 3 ELAS'EING PLUGBenjamin L. Lubeishy, Wynnewood, and Walter R. Waiburn, Shamokin, Paassignors to fieita man Safety Blasting Plug Com, Shamokin, Pa... acorporation of Pennsylvania Application January 30, 1941, Serial No.376,834

1 13 Claims.

This invention relates to improvements in blasting plugs of the typecomprising a radially enpandible plug body which, after insertion in abore hole, isexpanded against the wall of the hole by means of internalpressure applied usually through the medium of a tapered expanderelement.

Heretoiore, it has been the conventional practice to form the expandiblebody of the plug in part or in whole of flexible rubber or rubbercomposition. These plugs, while highly satisfactory for certainpurposes, are not well adapted for blasting operations in closed spaces,such as mines, by reason of the malodorous fumes resulting from thecombustion of the rubber composition and, sometimes, of the fire hazard.

a principal object of the present invention is to provide a plug of thestated type which shall not be subject to the aforesaid objectionableproperties of the conventional rubber plug.

More specifically, an object of the invention is to provide a plug ofthe stated type which shall be composed of a material which is eitherinherently incombustible or which, if combustible,

will not generate noxious or objectionable fumes.

The inventionfurther contemplates provision of a plug which shall berelatively inexpensive to manufacture, less subject to deterioration,and substantially more eficient than plugs of the prior type Theinvention further resides in certain novel (oi. ce-soy structuralfeatures hereinafter described and illustrated in'the attached drawings,wherein:

Figure l, is a view in perspective of a plug made in accordance with thinvention, the two major elements of the plug, namely, the expandiblebody and the tapered expander, being separated;

Fig, 2 is a vertical sectional view of the plug showing the aforesaidmajor elements in the initial position and prior to expansion;

Fig. 3 is a fragmentary sectional perspective view illustrating one typeof material of which the body of the" plug is formed;

Fig. i is a fragmentary sectional view on the line i-d, Fig. 3;

Figs. 5 and 6 are fragmentary top end views of the plug bodyillustrating successive steps of manufacture;

Fig. 7 is a view corresponding to those of Figs. 5 and 6 showing thebody of the plug in its expanded condition;

Fig. 8 is a view corresponding to that of Fig. 4 illustrating a modifiedform of body structure;

Fig. 8a is a view corresponding to Fig. 8 and illustrating a preferredform of body structure cylindrical form of the body, as illustrated inemploying a crlmped or folded sheet materia or s n le pl Fig. 9 is .acorresponding view showing still another type of base material which maybe used to advantage in the manufacture of the plug body; a Y

Fig. 10 is a fragmentary sectional view showing the base materialillustrated in Fig. 9 as compressed in an initial step of producing theplug body;

Fig. 11 is a fragmentary view in perspective of still another type ofbase material which has been found suitable for the production of plugsin accordance with the invention;

Fig. 12 is a fragmentary end view of a plug body made of the materialshown in Fig. 11, and Fig. 13 is a view in perspective of a modifiedform of plug body falling within the scope of the invention.

With reference to Figs. 1 and 2 of the drawings, the plug thereinillustrated comprises a substantially cylindrical hollow body member iwhich in the'present instance is composed of an insame material as thebody i and which closes one.

end of the central cylindrical bore 4 of the body.

The other end of the bore s is left open for reception of a suitabletapered expansion element 5 which maybe made of wood or other suitablematerial and which preferably is provided at its reduced end with asubstantially cylindrical extension 6, which as shown in Fig. 2 isadapted to neatly fit within the open end of the bore 6 of the bodymember.

As previously set forth, the body member I is made of an inherentlysubstantialy non-stretchable material, such as paper. In the productionof the body, this material in sheet form is folded or crlmped, asillustrated in Figs. 3 and 4, and the crimped mass then shaped to theform of the finished body member with the contiguous folds 1 arrangedmore or less radially and providing for the necessary radial expansionof the walls of the body. In producing the cylindrical body of the plug,a section of the crimped or folded material of suitable length is shapedinto the Fig. 5, which figure shows a segmental portion of the completecylinder. In this-initial cylindrical form, the folds or crimps i extendin substantially exact radial direction, as illustrated in Fig. 5, andin this condition, the outer ends of the folds are separated, leavingtherebetween voids 8 which extend inwardly and'substantially radially ofthe cylindrical body. The wall of the cylindrical body thus produced isthen compressed in a suitable die or mold in a manner to increase theinternal diameter of the cylinder and to deflect the folds 1 from theoriginal radial positions to the positions shown in Fig. 6 in which theyare somewhat inclined to the radius. This compression of the wall of thebody and the resulting deflection of the folds I as described has theeflfect,

as illustrated in Fig. 6, of substantially eliminating the voids 8 andaffording a wall formation in which the folds 1 lie flatly against eachother. If now the body as a whole is expanded radially, as illustratedin Fig. 7, thefolds assume an even closer relation, with a substantialsolidification of the wall of the body.

It will be noted by reference to Figures 3 and 4 that the sheet materialof which the body is composed as described above is, in the presentinstance, composed of two plies designated respectively 9 and ill. Thedepth of the folds in the ply I0 is somewhat greater than the depth ofthe folds of the ply 9, and the folds are so relatively arranged that atone side the edge portions if of the folds of the ply l0 extend beyondthe corresponding edges l2 of the folds of the ply d. When the crimpedtwo-ply sheet is shaped to the cylindrical form of the plug body, asshown in Fig. 5, the projecting edge portions N form the innerperipheral portion of the body. Thus each of the folds T has a greatermass of material in the outer than in the inner part, and this conditionassists in the subsequent compacting or compressing operation, in whichas previously described the wall of the body is substantially solidifiedand freed from voids. This device, in other words, provides for agreater mass of the material in the outer peripheral portion of the bodymember and a lesser mass of the material in the inner peripheral portionprior to the compacting operation illustrated in Fig. 6 and describedabove, so that after this operation, the mass of the -materia1 in thevarious portions of the wall of the body is more nearly uniform.

It ls apparent, however, that in the production of a plug body inaccordance with the invention, a single ply crimped sh'eet l3 of thegeneral character shown in Fig. 8 may be used, although where a singleply sheet is used, it is preferable to form the crimps or folds as shownin Fig. 8a. In this case, the interspersed arrangement of major andminor folds affords. substantially the same effect obtained by thetwo-ply folded sheet illustrated in Figs. 3 and 4 and described in thepreceding paragraph. Substantially the same effect afforded by thetwo-ply crimped sheet illustrated in Figs. 8 and 4 may be obtained byuse of a composite corrugated structure of the character illustrated inFig. 9. In this instance, the composite material comprises a plane sheetH, to one face cf'which is adhesively or otherwise attached a corrugatedsheet l5. When this blank is crimped on lines I6 extending through theapices of the corrugations of the component sheet l5, a crimped body isobtained corresponding to that illustrated in Fig. 10, it being notedthat the mass of material in the one face portion ll of this body ismaterially greater than the mass of the material in the other faceportion 18. In forming this crimped body into the shape of the hollowcylindrical plug, the portion l8 will con- 4 stitute the innerperipheral part of the plug body, and the portion I! the outerperipheral part.

A highly desirable type of composite material for use in the productionof plugs in accordance with the invention is illustrated in Fig. 11.This material is of the conventional corrugated cardboard type,consisting of two plane sheets I! and 20 which are spaced apart andJoined together by an intervening corrugated sheet 2|. In this case, thecorrugations of the intermediate sheet, preferably, are relatively smallas compared with the depth of the folds or crimps in the finished bodyof the plug. The small corrugations of the intermediate sheet 2| havethe faculty of adjusting themselves to the changes of form resultingfrom the initial crimping of the material and the subsequent shaping ofthe crimped mass into the fprm of the hollow cylinder of the plug body,as illustrated in Fig. 12, with the result that the radially expandiblewall of the finished plug exhibits a high degree of solidity and freedomfrom undesirable voids.

As previously set forth, the material of which the body of the plug isproduced in accordance with the invention described above may becomposed of paper or cardboard. It is apparent, however, that sheetmaterial of any composition or internal structure, which is capable ofbeing shaped to the required crimped or folded form and which has theessential characteristic of flexibility coupled with a degree ofmoldability, may be used in a practice .of the invention. Wherenon-combustible characteristics are required, the base material maysuitably be composed of asbestos. Since the character of constructionpossesses certain advantages of simplicity, economy, and functionalefllciency which at least in part are independent of the materials used,there is no restriction in this respect either real or implied.

As illustrative of a possible modification within the scope of theinvention, we have shown in Fig. 13 a plug body composed of moldedfibrous material, such as flexible paper or asbestos board. In thiscase, the molded monolithic wall of the hollow plug body is ofcorrugated contour, and preferably the corrugations 22 are spirally orotherwise arranged so that they extend longitudinally of the plug at anangle to the longitudinal axis of the latter. These corrugations, asalso do the folds or crimps of the previously described embodiments,afiord in effect longitudinal reentrant portions in the wal1 of the bodywhich, by providing for increase in the effective circumferentialdimension of the wall, permit the required expansion of the bodyradially of the longitudinal axis. The molded fibrous material isinherently flexible to permit the corrugations to straighten out underthe-effect of pressure internally applied through the medium, forexample, of an expander element of thegeneral character shown in Figs.'1 and 2. The said fibrous material may be water-bonded, or may bebonded through the medium of any suitable agent, which preferably willbe of a non-combustible character or in any event of a character whichshall not be productive upon combustion of objectionable fumes or odors.It will be understood that in this embodiment of the invention, as inthose previously described, one end of the plug body will be closed orsealed by means of a suitable closure element (not shown) correspondingto the cap illustrated in Fig. 2.

If, in expanding this plug in the bore hole, the corrugations are notcompletely extended, the

b inclination of the remaining voids between the wall of the hole andthe plug body to the longitudinal axis of the hole will act in effect asa gas trap and will retain the full effect of the blast inthe hole.

We claim:

1. A blasting plug comprising a substantially tubular body composed offlexible sheet material, the wall of said body exhibiting a plurality ofpleats extending longitudinally of the body in planes intersecting theinner and outer surfaces of said wall and being formed so as to providea greater mass of said material in the outer circumferential portion ofthe wall than in the inner portion, said pleats providing for increasein the eflective circumferential dimension of the wall and expansion ofsaid body radially with respect to its longitudinal axis.

2. A blasting plug comprising a substantially tubular body composed offlexible sheet material, the wall of said body exhibiting a plurality ofpleats extending longitudinally of the body in planes intersecting theinner and outer surfaces of said wall, certain of said pleats being ofrelatively great depth radially'of said body and be ing interspersedwith others of said pleats of lesser depth, the pleats of lesser depthbeing confined to the outer circumferential portion of the body so as toprovide in that portion a greater mass of said material than in theinner portion, said pleats providing for increase in the effectivecircumferentialdimension of the wall and expansion of said body radiallywith respect to its longitudinal axis.

3. A blasting plug comprising a substantially tubular body composed offlexible sheet material, the wall of said body exhibiting a plurality ofpleats extending longitudinally of the body in planes intersecting theinner and outer surfaces of said wall and providing for increase in theeffective circumferential dimension of the wall and expansion of saidbody radially with respect to its longitudinal axis, the individualpleats having a multiple ply of said sheet material in the portionsthereof which are more remote to the axial center of said body. 4

4. A blasting plug comprising a substantially tubular body composed offlexible sheet material, the wall of said body exhibiting a plurality ofpleats extending longitudinally of the body in planes intersecting theinner and outer surfaces of said wall and providing for increase in theeifective circumferential dimension of the wall and expansion of saidbody radially with respect to its longitudinal axis, the indivdualpleats having a greater number of plies of said sheet material in theportions thereof which are more remote to the axial center of said bodythan in the portions that are less remote to said center.

5. A blasting plug comprising a substantially tubular body composed ofcorrugated flexible sheet material, said material being folded so as toprovide in the wall of said body a plurality of closely set pleatsextending longitudinally of the body and providing for increase in theeffective circumferential dimension of the wall and expansion of saidbody radially with respect to its longitudinal axis.

6. A blasting plug comprising a substantially tubular body composed offlexible sheet material, said material comprising two flat surface websand an intermediate corrugated web and being folded so as to provide inthe wall ofsaid body a plurality of closely set pleats extendinglongitudinally of the body, said pleats providing for increase in theeffective circumferential dimensionofthewallandexpansionofsaidbodyradially with respect to its longitudinal axis.

'1. A blasting plug comprising a substantially tubular body composed offlexible sheet material,

ness materially in excess of the'thickness of saidsheet material andproviding for increase in the effective circumferential dimension of thewall and expansion of the body radially with respect to the longitudinalaxis of the bore.

8. A blasting plug comprising asubstantially tubular body composed offlexible sheet material, the wall of said body exhibiting a plurality ofpleats with edges disposed at the inner and outer peripheral surfaces ofthe wall and extending longitudinally of the tubular bore of the body,said pleats providing for increase in the effective circumferentialdimension-of the wall and expansion of the body radially with respect tothe longitudinal axis of said bore, and the longitudinal edges of thepleats being contiguous so as to afford substantially even andcontinuous inner and outer wall surfaces.

9. A blasting plug comprising a substantially tubular body composed offlexible sheet material, the wall of said body exhibiting a plurality ofpleats with edges disposed contiguously at the inner and outerperipheral surfaces of the wall and extending longitudinally of thetubular bore tudinal axis of said bore.

10,. A blasting plug comprising a substantially tubular body composed offlexible sheet material,

the wall of said body exhibiting a plurality of pleats with edgesdisposed at the inner and outer peripheral surfacesof the wall andextending longitudinally of the tubular boreof the body. said pleatslying substantially fiat in face to face relation and having their outerlongitudinal edge portions of greater thickness than the lnner edgeportions so as to afford a compact wall having inner and outersubstantially even and continuous surfaces and capable of expansion asto the effective circumferential dimension of the wall and radially withrespect to the longitudinal axis of said bore.

11. A blasting plug comprising a substantially tubular body composed offlexible sheet material,

the wall ofsaid body exhibiting a. plurality of pleats with edgesdisposed at the inner and outer peripheral surfaces of the wall andextending longitudinally of the tubular bore of the body,

said pleats lying substantially flat in face to face relation and havingtheir outer longitudinal edge portions of greater thickness than theinner edge portions so as to afl'ord a compact wall having Qsubstantially even inner and outer surfaces and of thickness materiallyin excess of the thickness of said sheet material, and said pleats lyingindividually in planes tangent to a circle concentric with the axis ofsaid bore.

.12. A blasting plug comprising a substantially tubular body composed.of flexible sheet material,

aaoassc said material being folded so as to provide in the wall of saidbody a plurality of closely set con-' longitudinal axis, the innerlongitudinal edges of said pleats being in contacting relation with eachother so as to form a substantially even and continuous surface in theinterior of the tubular 13: A blasting plug comprising a. substantially.8 I tubular body composed of corrugatedflexible sheet material, saidmaterial being folded so as to provide in the wall of said body aplurality of closely set contracted pleats extending lonaitudi-z nallyof the body and providina' for increase in the effective circumferentialdimension of tin wall and expansionof said body radially with respect toits longitudinal axis, said pleats lying flatly one against another soas to provide a compact wall formation substantially free from'v'oids.

mums L. Lunmsxr.

WALTER R. WALBURN.

